Injection Molding Data – 20 Plastic Properties（Up）

PC/ABS polycarbonate and acrylonitrile butadiene styrene copolymer and mixture

Typical applications: computer and commercial machine housings, electrical equipment, lawn gardening machines, automobile parts dashboard, interior decoration and wheel covers).

Injection mold process conditions: drying treatment: drying treatment before processing is necessary. The humidity should be less than 0.04%, and the recommended drying condition is 90~110C for 2~4h. Melting temperature: 230~300C. Mold temperature: 50~100C. Injection pressure: depending on the plastic part. Injection speed: as high as possible.

Chemical and physical characteristics: PC/ABS has the comprehensive characteristics of PC and ABS. For example, ABS is easy to process and PC has excellent mechanical properties and thermal stability. The ratio of the two will affect the thermal stability of PC/ABS materials. The PC/ABS composite also shows excellent flow characteristics. The shrinkage is about 0.5%.

Mixture of PC/PBT polycarbonate and polybutylene terephthalate

Typical application range: gear box, automobile bumper and products requiring chemical reaction resistance, corrosion resistance, thermal stability, impact resistance and geometric stability. Injection mold process conditions: drying treatment: 110~135C, about 4 hours of drying treatment is recommended. Melting temperature: 235~300C. Mold temperature: 37~93C. Chemical and physical characteristics: PC/PBT has the comprehensive characteristics of PC and PBT, such as high toughness and geometric stability of PC, chemical stability, thermal stability and lubrication characteristics of PBT, etc. The shrinkage is about 0.5%.

Typical application scope of PE-HD high-density polyethylene: refrigerator containers, storage containers, household kitchenware, sealing covers, etc.

Injection mold process conditions: dry: no need to dry if properly stored. Melting temperature: 220~260C. For materials with large molecules, it is recommended that the melting temperature range be 200~250C. Mold temperature: 50~95C. Plastic parts with a wall thickness of less than 6mm shall use a higher mold temperature, and plastic parts with a wall thickness of more than 6mm shall use a lower mold temperature. The cooling temperature of plastic parts shall be uniform to reduce the difference of shrinkage. For the optimal processing cycle time, the diameter of the cooling channel should not be less than 8mm, and the distance from the mold surface should be within 1.3d (here “d” is the diameter of the cooling channel). Injection pressure: 700~1050bar. Injection speed: High speed injection is recommended. Runner and gate: The runner diameter is between 4 and 7.5 mm, and the runner length should be as short as possible. Various types of gates can be used, and the gate length shall not exceed 0.75 mm. It is especially suitable for hot runner molds.

Chemical and physical properties: The high crystallinity of PE-HD leads to its high density, tensile strength, high temperature distortion temperature, viscosity and chemical stability. PE-HD has stronger permeability resistance than PE-LD. The impact strength of PE-HD is low. The properties of PH-HD are mainly controlled by density and molecular weight distribution. The molecular weight distribution of PE-HD suitable for injection mold is very narrow. For the density of 0.91~0.925g/cm3, we call it the first type PE-HD; For the density of 0.926~0.94g/cm3, it is called the second type PE-HD; For the density of 0.94~0.965g/cm3, it is called the third type PE-HD. The material has good flow characteristics, with MFR between 0.1 and 28. The higher the molecular weight, the worse the flow characteristics of PH-LD, but it has better impact strength. PE-LD is a semi crystalline material with high shrinkage after molding, which is between 1.5% and 4%. PE-HD is prone to environmental stress cracking. Cracking can be reduced by using materials with very low flow characteristics to reduce internal stresses. PE-HD is easy to dissolve in hydrocarbon solvents when the temperature is higher than 60C, but its anti solubility is better than PE-LD.

Typical application scope of PE-LD low-density polyethylene: bowl, cabinet, pipe coupler

Process conditions of injection mold: drying: generally, no melting temperature is required: 180~280C Mold temperature: 20~40C In order to achieve uniform cooling and more economical heat removal, it is recommended that the diameter of the cooling chamber should be at least 8mm, and the distance from the cooling chamber to the mold surface should not exceed 1.5 times of the cooling chamber diameter. Injection pressure: up to 1500bar. Pressure maintaining pressure: up to 750bar. Injection speed: fast injection speed is recommended. Runners and gates: Various types of runners and gates can be used PE is particularly suitable for using hot runner molds.

Chemical and physical properties: density of commercial PE-LD material is 0.91~0.94 g/cm3. PE-LD is permeable to gas and water vapor. PE-LD has a very high coefficient of thermal expansion, which is not suitable for processing products used for a long time. If the density of PE-LD is between 0.91 and 0.925 g/cm3, its shrinkage is between 2% and 5%; If the density is between 0.926 and 0.94 g/cm3, the shrinkage is between 1.5% and 4%. The actual shrinkage at present also depends on the injection molding process parameters. PE-LD can resist many solvents at room temperature, but aromatic hydrocarbon and chlorinated hydrocarbon solvents can expand it. Similar to PE-HD, PE-LD is prone to environmental stress cracking.

Application scope of PEI polyetherimide: automobile industry (engine accessories such as temperature sensors, fuel and air processors, etc.), electrical and electronic equipment (electrical connectors, printed circuit boards, chip shells, explosion-proof boxes, etc.), product packaging, aircraft internal equipment, and pharmaceutical industry (surgical instruments, tool shells, non implantable instruments).

Injection mold process conditions: drying treatment: PEI has hygroscopic properties and can lead to material degradation. The humidity value is required to be less than 0.02%. The recommended drying condition is 150C for 4 hours. Melting temperature: 340~400C for ordinary materials; The reinforcement type material is 340-415C. Mold temperature: 107~175C, recommended mold temperature is 140C. Injection pressure: 700~1500bar. Injection speed: Use the highest possible injection speed.

Chemical and physical properties: PEI has strong high-temperature stability, even if it is non reinforced, it still has good toughness and strength. Therefore, PEI’s superior thermal stability can be used to make high-temperature and heat-resistant devices. PEI also has good flame retardancy, chemical resistance and electrical insulation properties. The glass transition temperature is very high, reaching 215C. PEI also has a very low shrinkage (generally 0.4% – 0.7%) and good isotropic mechanical properties.

Typical application scope: automobile (dashboard, tool cabin door, wheel cover, reflector box, etc.), refrigerator, high-intensity tools (hair dryer, mixer, food processor, lawn mower, etc.), telephone shell, typewriter keyboard, entertainment vehicles such as golf cart and jet sled, etc.

Process conditions of injection mold: drying treatment: ABS material has hygroscopicity, and drying treatment is recommended before processing. It should be dried for at least 2 hours at 80~90C. The material temperature shall be less than 0.1%. Melting temperature: 210~280C; Recommended temperature: 245C. Mold temperature: 25… 70C. Mold temperature will affect the finish of plastic parts, and lower temperature will lead to lower finish). Injection pressure: 500~1000bar. Injection speed: medium high speed.

ABS is synthesized from acrylonitrile, butadiene and styrene. Each monomer has different characteristics: acrylonitrile has high strength, thermal stability and chemical stability; Butadiene has toughness and impact resistance; Styrene is easy to process, high finish and high strength. In terms of morphology, ABS is an amorphous material. The polymerization of three monomers produces a ternary copolymer with two phases, one of which is a continuous phase of styrene acrylonitrile,

The other is polybutadiene rubber dispersed phase. The properties of ABS mainly depend on the ratio of three monomers and the molecular structure of two phases. This allows great flexibility in product design, and leads to hundreds of different quality ABS materials in the market. These different quality materials provide different characteristics, such as medium to high impact resistance, low to high finish and high temperature distortion characteristics. ABS material has excellent processability, appearance characteristics, low creep, excellent dimensional stability and high impact strength